Radix Sort is Fun… but it’s Useless in JavaScript

I just spent an hour writing a Radix sort algorithm. It turns out that it is 25% the speed of the built in JavaScript `.sort()` function.

Apparently all this sorting has been figured out in the past. Strange that it’s part of learning to code these days…

const performance = require('perf_hooks').performance;


function getDigit(num, location) {
  let stringNum = num.toString();
  let resultNum = parseInt(stringNum[stringNum.length - 1 - location]);
  if (resultNum) {
    return resultNum;
  } else {
    return 0;
  }
}

function getDigitCount(num) {
  let digitCount =  Math.abs(num).toString().length;
  return digitCount;
}

function mostDigits(arr) {
  let maxDigits = -Infinity;
  for (var i = 0; i < arr.length; i += 1) {
    var digitCount = getDigitCount(arr[i])
    if (maxDigits < digitCount) {
      maxDigits = digitCount;
    }
  }
  return maxDigits;
}

function radixSort(list) {
  let numberOfDigitsTheLargestNumberHas = mostDigits(list);

  for (let i = 0; i < numberOfDigitsTheLargestNumberHas; i += 1) {
    let bucket = [[],[],[],[],[],[],[],[],[]];

    for (var j = 0; j < list.length; j += 1) {
      let number = list[j];
      bucket[getDigit(number, i)].push(number);
    }
    list = bucket.flat(2);
  }
  return list.flat();
}

function sum(a, b) {
  return a - b;
}

var ourBeautifulArray = [50000, 1200,1133, 44, 22, 1, 400000000];
var time1 = performance.now();
console.log(radixSort(ourBeautifulArray));
var time2 = performance.now();
console.log(`RadixSort took ${time2 - time1} to execute`);

var time3 = performance.now();
console.log(ourBeautifulArray.sort(sum));
var time4 = performance.now();
console.log(`Normal JS sort took ${time4 - time3} to execute`);

It’s possible that there is room for improvement in the way I’m executing this algorithm. Perhaps using .flat┬áis causing this.

Either way, even if it’s not a useful thing to be able to do, I think it’s interesting. Once you figure out how it works, it’s neat because it sorts things in non-obvious ways.

I just wish it performed better. LoL

If you want to see the code I’m working with to deepen my knowledge of JavaScript, check out this repository.

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